Observe the graph, the point
lies on the graph and y varies directly with x and the line passes through the origin.
So, the equation has the form
.
Substitute the values of
in the direct variation equation
to find a.

Divide each side by 4.
\
.
The direct variation equation that relates x and y is
.
If
, then
.
The direct variation equation that relates x and y is
and the value of
.